In the dispensing of viscous fluid for dual extrusion to produce a striped output such as for striped toothpaste, it has become common to utilize a piston in a container that is movable to dispense a primary portion from a first chamber and a second portion from a second chamber, the two portions blending to form a striped product. A typical arrangement is shown in U.S. Pat. No. 4,461,403. Such dispensers utilize a chamber for the first component or portion and a small chamber for the second component or portion, the latter being made by a rigid or integral insert within the container.
The size of the insert determines not only the amount of material which can be dispensed from the second chamber but also the amount of material dispensed from the first chamber since the insert functions as a stop for the moving piston.
Among the objectives of the present invention are to provide a dispenser which utilizes an axially compressible sleeve insert permitting a larger amount of the striping material to be dispensed and at the same time permitting substantially more of the material to be dispensed from the second chamber, thus minimizing the amount of unused material left within the container after the sleeve moves to its maximum position.
In accordance with the invention, a dispenser for dual extrusion of striped viscous fluids such as toothpaste or the like comprises a container having an opening, an axially collapsible sleeve insert inserted in the opening, and a piston engaging one end of the sleeve insert. The container is adapted to contain a first viscous material which extends into the sleeve. A second viscous fluid material is provided about the sleeve. The sleeve has a first set of openings at one end adjacent the piston for passage for the first viscous fluid material and a second set of openings therein spaced from the first set of openings and adjacent the opening in the container. Ribs are provided adjacent the other end of the sleeve insert and adjacent the second set of openings for guiding the second material into dual striping extrusion with the first material.